Paraffin scraper



Nov. 18, 1958 R. BRYANT, JR 2,860,710

PARAFFIN scRAPER Filed Aug. e. 1954 s sheets-sheet 1 1N V EN TOR.

A//s A 'from/EY Nov. 18, 1958 R. BRYANT, JR 2,860,710

PARAFFIN SCRAPER Filed Aug. 6. 1954 l 3 Sheets-Sheet 2 #AS ATTRNE'Y Nov.18, 1958 R. BRYANT, .JR

PARAFFIN SCRQPER 5 Sheets-Sheet 3 Filed Aug. 6. 1954 United StatesPatent ON PARAFFIN SCRAPER Randolph Bryant, Jr., Houston, Tex., assignorto `Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Penn-Sylvania `Application August 6, 1954, Serial No. 448,308 4` Claims. (ci.16s- 173)` This' invention relates to a paraffin scraper especiallyuseful in removing the accumulation of paratiin depositedorrthe'interior'surface of How pipe in flowing and gaslift oil wells.yIn oil wells it has been found that Where 'the effluent containsparaffin, paraflin is deposited on the inner surface of the flow pipe sothat removal of the parainis essential in order to maintain normalproduction of the welll Various solutions for this problem have beenproposed, such as the use of Scrapers mechanically operated from thesurface, solvents, and Scrapers operated by means of the force ofgravity and the energy of the oil flowing in` the-flow pipe. The presentinvention is concerned with a scraper of the last-named type. Thescraper ofthe-invention has the advantages of being uncompli- "cated indesign and economical to manufacture and repair.

The details ofconstruction and operation of the scraper are more fullydescribed hereinafter, reference being ma'de to the `accompanyingdrawings which constitute a part hereof, wherein like numerals refer tolike parts throughout and in which:

`Figure 1 is a longitudinal sectional View of a flow pipe showing thelower part of the scraper therein in longitudinal cross section; i l

-Figure 2 is a longitudinal sectional View of a flow pipe showing thecenter part of the embodiment of the scraper shown in Figure 1 inlongitudinal cross section.

Figure 3 is a longitudinal sectional view of the `upper part of theembodiment of the scraper shown in Figures l and 2 in longitudinal crosssection.

Figure 4-is a longitudinal sectional View of the 'upper part of anotherembodiment of the invention in longitudinal cross section.

`Figure 5 is a longitudinal `sectional View of a ow pipe containing theupper part of the scraper shown in longitudinal cross section toillustrate a different structure for controlling-.the reciprocatingmotion of the parts of the scraper.

Figure 6 is `a cross section of thel scraper taken along line VI--VI-ofFigure 5.

|Figure 7 is a longitudinal sectional view of a flow pipe containing thescraper therein and showing the upper and lower .limits within which thescraper is intended to operate.

Referring to Figures 1, 2 and 3 in detail, wherein for the pur-pose ofillustration is disclosed a preferred embodiment of my invention, thereis shown an oil producing tubing or ow pipe 10 in which is placed theparaffin' scraper which is designated generally by the numeral 11. Ahollow cylinder 12 `is placed Within the oil producing tubing" or flowpipe between upper and lower stops (Figure" 7) arranged at the upper andlower limits between which it is desired to remove parain deposited inthe ilow pipe. Stops 58 and 59, consisting of horizontal bars welded orfastenediby other suitable means across the inside diameter of the ilowpipe 10, are located at the upper and lower limits` within which thescraper is intended to p'peratelr It will be understood that any othersuitable '2,860,710 Patented Nov. 18, 1958 type of stops which `wouldnot obstruct the fluid flow in flow pipe 10 could be employed. The upperstop may be fixed in an upper section of the ow pipe to permit theinsertion and removal of the scraper by disconnecting the varioussections of the flow pipe. Attached to and forming a part of the lowerend of cylinder 12,` is a circular blade `13 of a size such that thereis a slight clearance between its periphery and the inner surface of theflow plpe.

Within the hollow cylinder 12 is a rod 14 such as a conventional suckerrod, of substantially smaller diameter than the inner diameter of thecylinder, and centrally positioned at its upper end within cylinder 12by arcuate positioning springs 15. These springs are ttedl into suitablekey slots 16 in rod 14 which are of such length as to permit movement ofthe lower end of springs 15 when under compression. The ysprings `^15are compressed in passing over an indented annular neck 17 whichprotrudes from the inner surface of cylinder 12. The neck 17 serves as adetent for the springs 15, to lmaintain the relative positions ofcylinder 12 and rod 14 during normal operation by positioning rod 14centrally with relation to cylinder 12 and by preventing verticalslipping. Valve element 1'8 has an integral portion of its structureextending downward below the valve structure forming an extension 23which effectively operates as an extension of rod v1-4. Extension 23 isthe lowermost portion of scraper 11 in all positions, and is thatportion of the scraper which strikes the lower stop S9 when suc-hcontact is made. How-. ever, upon striking the lower stop for thedownwardv motion of the scraper, the impact of arrested motion issufcient to cause -positioning springs 15 to `compress and pass overannular neck 17. Thereafter the positioning springs resume theirnon-slipping function until the upper end of rod 14 makes contact withthe upper stop, whereby springs 15 are again caused to compress and passover the annular neck. Three such springs will normally be used, each ofwhich is separated from the others by of arc. i

A cup-shaped valve element 18 surrounds and is attached to the lowerpart of rod 14 by threaded means 19. This member functions as oneelement of the valve to be described. The upwardly extending rim 20 ofvalve element 1'8 fits slidably within the lower end 22 of cylinder 12.Rim 20 contains ports 21, shown as U-shaped slots, through which oil mayHow when these ports are not covered by the lower end 22 of cylinder 12.An extension 23 of valve element 18 extends below the lower end 22 ofcylinder 12 and is the part of the scraper to make contact when thescraper strikes the lower stop.

Two blocks 24 and 24a are positioned at right angles to one another inclosely fitting slots in rod 14 and extendbeyond the rod on both sides.lThe extensions of block 24 shown at 25 t slidably withinv slots 26 incylinder 12. Slots 26 are longer than block 24 the excess length beingthe distance of relative longitudinal movement between rod 14 andcylinder 12 required for covering and uncovering' ports 21 in valveelement 18. The parts 27 of extensions 25 extend through and beyond theSlots in the walls of cylinder 12 and function as an aid in positioningthe scraper 11 centrally within the flow pipe 10. The `parts 27 and 27aof blocks 24 and 24a extend very close to the inner surface of flow pipe10 so that if and when scraper 11 deviates from a concentric positionwithin the ow pipe the extended portions 27 and 27a of blocks 24 and 24awill be the lirst part or parts of the scraper to touch the innersurface of the ow pipe and will function as rails or skids to direct andstraighten the motion of the scraper until it is once more movingparallel to the inner surface of the ow pipe. It will be understood thatalthough parts 27 and 27a extend close to the inner surface of the owpipe they are not in contact except upon deviation of the scraper frommotion parallel to the inner surface of the ow pipe. A layer ofdeposited parain coats the inner surface of the flow pipe providing alubricating means. If some clearance were not allowed between parts- 27and l27a`and the inner wall of the ow pipe the scraper might littoosnugly and the presence of paran might cause thescraper to jam in the-tlow pipe.l :It will be understood that block 24a is provided withextensions similar to `rod 14 extend beyond the upper end of cylinder 12in order to make'contact with the upper Ystop and Iin order to be easilyaccessible to a fishing tool.

fIn the operation Vof the device shown in Figures l, 2 and 3, theparaffin scraper 11 is placed in the flow pipe with rod 14 atitslowermost position with relation to cylinder 12 as shown in Figure l. Inthis position the 'springs 15 are below annular neck 17, see Figure 3,po-

sitioning blocks 24 and 24a are at their lowermost position in slots 26and 26a provided in cylinder 12, see Figure 2, and ports 21 in theupwardly extending riml 20 of valve element 18 are uncovered as -shownin FigureV 1, permitting the upward flow of oil in the flow pipe,through ports 21 and upward through the interior of cylinder -12. Inthis position the scraper falls by its weightv and circular blade 13scrapes off the accumulation of paran from the interior surface of flowpipe 10. The paran thus detached is washed through ports 21, upwardthrough cylinder 12 and on up the ow pipe by the upward flow 'of fluid.This flushing action constitutes an important advantage of the inventionas the removed parafln isnot deposited in the relatively dead spaceoutside of the body of the scraper and therefore cannot accumulate onthe outside of the tool and cause it to stick in the flow pipe. When thefalling scraper 11 reachesA the lower stop, 59, the extension 23 ofvalve element 18 attached to the lower end of rod 14 strikes the stopwith considerable impact lcausing cylinder 12 to slide downward withrelation to rod y14. In this position the lower end 22v of cylinder 12covers ports 21 thus preventing the flow of oil upward through ilow pipe10. The distance traveled 'bycylinder 12 with relation to rod 14 afterthe scraper strikes the upper and lower stops is limited by the lengthof slots 26 and 26a in cylinder 12 in which blocks 24 and 24a areguided. With ports 21 in valve element '18 closed, the free upward flowof oil in the ilow pipe is substantially obstructed and sealed oi sothat scraper 11 is forced upward by the flow of oil in the flow pipeuntil head 34 attached to rod 14 strikes the upper stop 58. The suddenimpact arresting upward movement of rod 14 causes cylinder 12 to travelupward with relation to the rod '14' and with relation to valve element18 thereon thus uncovering ports 21 and permitting the free owlof oilthrough these ports and upward through cylinder 12. Upward pressure onthe scraper being thereby relieved, the scraper falls in flow pipe 10 byits weight repeating the operation described.

-It will be understood that the embodiment shown in Figures l, 2 and 3can be modified in certain respects without departing from the scope ofthe invention. For example, in a case where itis desired to accomplishscraping of the flow pipe during the upward movement of the scraper aswell as during its downward movement, the scraper may be provided withanother scraper blade 13a, which is similar but not identical to blade13, and is attached adjacent the upper end 42 of cylinder 12. Such ablade is shown in Figure 4. The blade shown there isy cylindrical inshape and attached to rod 14 by two or more rigid arms 43 at a pointabove the uppcr'end42 of cylinder 12, an annular space being providedbetween the lower end of blade 13a and the upper end 42 of cylinder 12as shown in Figure 4.

Referring to Figure 4, there is disclosed another embodiment of theinvention in which a sleeve valve is disposed in the upper end of thecylinder 12. It will be understood that this valve would normally beemployed in `place of the valve shown in Figure l. In this embodimentthere is attached to a shoulder 37onjrod14, a cylindrical valve element38 having ports 39. VThese ports are disposed at intervals around thecircumference of the valve element 38. The upper end of cylinder 12 inthis embodiment is provided with corresponding ports 41. The operationof the scraper involves the downward movement of cylinder 12 when thescraper strikes the lower stop in the flow pipe. On this impact, theimperforate section 42 of cylinder 12 slides downwardly to cover ports39. As a result, the flow of oil through the scraper is prevented andthe scraper is caused to move upwardly by the upward flow of uid in thewell until it strikes the upper stop. When this occurs the .cylinder 12is forced upwardly with relation to rod 14 forv ajdristance limited byextensions 25 and 25a of rod 14 moving in slots 26 and 26a. At thispoint in the movementgof the scraper in the ow pipe, the relativelongitudinal positions of the valve element 38 and cylinder 12 willbe asshown in Figure 4. With ports 39 and 41, coinciding, theflow of oilproceeds upward through cylinder 12 and ,out through valve ports 39 and41, upward in yiiowpipe `10 Voutside the upper end 42 of cylinder 12,through the annular space between the upper end 42 of cylinders12 andthe lower end of the upper blade -13a,1,upward through the interior ofcylindrical blade 13a and on up,- ward in ow pipe 10. As the upward flowof oil is unobstructed the scraper is caused by gravity to fall down;wardly in the tlow pipe, counter to the uid flow,unti1 the lower stop isreached. f

When a valve is used at the upper end of cylinder f'12, as abovedescribed, it is advantageous to provide short cylindrical sleeves 57and 57a attached below positioning blocks 24 and 24a within or outsideof cylinder`12.-i'n order to cover the open portions of slots 26 and26a-{dur-l ing the upward travel of the scraper so that the-hy draulicforce provided by the upward ow of uid elevating the scraper, is notlost by leakage throu'ghfthe open 'portions of the slots 26 and 26a, asshown'in EFigures l and 2. t A scraper blade attached adjacentI theupper endiyof cylinder 12 will normally be used only in conjunction witha scraper blade attached adjacent the lower-'end 'of the cylinder. Ascraper blade attached adjacent the lower end of cylinder 12 in thiscase is important,- because after the scraper strikes the lower stopwhich causes the valve mechanism of the scraper to` close, thecircumference of the scraper blade attached adjacent the lower end ofthe cylinder forms a seal between the scraper 11 and the inside of flowpipe 10, thus subjecting the scraper to the maximum amount of thehydraulic force exerted by the upward ow of oil in the flow pipe whichwill carry the scraper upward with the iluid ow until it reaches andstrikes the upper stop, which in turn causes the valve mechanism of thescraper to open, again plac-4 ing the scraper in position to traveldownward and re? peat the operation described. I

Referring now to Figures 5 and 6 there is shown a variation of theinvention providing a somewhat different structure as a means forcontrolling the longi-` tudinal reciprocating movement of rod 14 andcylinder 12, thereby respectively opening and closing the valve and 24a,thus eliminating blocks 24 and 24a, slots 2 6 and 26a, snap rings 29 and29a, and `grooves 28 and 28a. This modification will simplify themachining necessary to manufacture the scraper, provide a larger bearingsurface for impact loads when the tool hits the stops, and simplify theassembly and disassembly of the tool.

At the upper end of cylinder 12 attached by threaded means 44 is anextension 45 of cylinder 12 with a reduced diameter as at 46. Rod 14extends within the cylinder extension 45 and is joined by threaded means47 to block 48. An extension 14aof rod 14 is attached to block 48 bythreaded means 49. The extension of the rod 14a continues upward toattach to the neck 33a and head 34a by threaded means 32a. Block 48extends horizontally beyond rod 14 and 14a on both sides, fittingslidably within slots 51 provided in extension 45 for the accommodationof such block. At the upper end of slots 51, rigidly attached toextension 45 of cylinder 12, is a solid cylindrical member 50, having acentral channel 52 which extends therethrough, and in which rod 14a fitsslidably. The upper surface 53 of cylindrical member 5@ and the lowersurface 54 of said cylindrical member serve as bearing surfaces toabsorb the impact loads when the lower surface 55 of neck 33a and theupper surface 56 of block 48 respectively strike the upper and lowersurfaces of member 50.

When the scraper strikes the lower stop 59 in ow pipe 10, the impactforces cylinder 12 with its extension 45 and attached cylindrical member50 downward with respect to rods 14 and 14a and block 48. This downwardmovement is stopped by the lower surface 54 of cylindrical member 50striking the upper surface 56 of block 48. The described downwardmovement of cylinder 12 with relation to rod 14 covers ports 21 in theupwardly extending rim 20 of the valve element 18 attached to rod 14 asshown in Fig. l, thereby closing ports 21 and forcing scraper 11upwardly by the flow of fluid in flow pipe 10, as previously described.

When the scraper strikes the upper stop 58 in ow pipe 10, the impactforces cylinder 12 with its extension 45 and attached cylindrical memberS0 upward with respect to rods 14 and 14a. This upward movement isstopped by the lower surface 55 of neck 33a, striking the upper surface53 of cylindrical member 50. The upward movement of cylinder 12 withrelation to rod 14 uncovers ports 21 in the upwardly extending rim 20 ofvalve element 18 attached to rod 14 as shown in Fig. 1, thereby openingthe ports 21 and permitting the free flow of fluid upward in flow pipethrough the interior of scraper 11 so that the scraper is released fromthe elevating force of the fluid and is free to fall by its own weight,counter to the fluid flow in flow pipe 10, and in so doing to scrape theaccumulation of paraffin from the interior surface of ow pipe 10 byaction of scraper blade 13. Slots 51 are of suicient length so that whenblock 48 is in its lowermost position with relation to cylindricalmember 5l), a portion of the slots 51 is below block 48 and remain open,as is shown in Fig. 5, so that the upward passage of fluid withincylinder extension 45 is unobstructed.

In this embodiment of the invention, cylindrical member 50 acts as thestop to contro-l the reciprocal relative movement of rod 14 and cylinder12, and the length of rod 14a determines the extent of relative motion.The use of cylindrical `member 50 is also adavntageous in that itprovides larger bearing surfaces to absorb the impact loads when theupper surface 56 of block 48 and the `lower surface 55 of neck 33astrike its lower and upper surfaces respectively.

Gbviously many modications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof; therefore only such limitations should be imposed asare indicated `in the appended claims.

I claim: t

l. A paraffin scraper adapted for free longitudinal movement within anoil wel] flow pipe provided. with upper and lower stops in the path ofsaid scraper, said scraper comprising a hollow cylinder havinga'longitudina-l slot intermediate the ends thereof, a circular scraperblade attached adjacent an end of said cylinderand projecting outwardlytherefrom, a rod positioned axially within said cylinder, said rodhaving a lateral extension intermediate the ends thereof fittingslidably within said slot in said cylinder, said `slot and saidextension cooperating to limit the relative longitudinal movement ofsaid cylinder and said rod when said rod strikes a stop, a cup shapedsleeve valve element having ports therein mounted on said rod adjacentan end thereof, said sleeve valve element tting slidably within an endof said cylinder, whereby the ports in lsaid sleeve valve element areadapted to be alternately covered and uncovered by the relativelongitudinal movement of said cylinder and said rod.

2. A paraffin scraper adapted for free longitudinal movement within anoil well flow pipe provided with upper and lower stops in the path ofsaid scraper, said scraper comprising a hollow cylinder having at leasttwo longitudinal slots intermediate the ends thereof, a circular scraperblade attached adjacent an end of said cylinder and projecting outwardlytherefrom, a rod centrally positioned axially within and extendinglongitudinally beyond the ends of said cylinder, said rod having atleast two lateral extensions intermediate the ends thereof fittingslidably within said slots in said cylinder, said extensions and saidslots cooperating to lirnit the relative longitudinal movement of saidcylinder and said rod when said rod strikes a stop, a :cup shaped sleevevalve element having ports therein mounted on said rod adjacent an endthereof, said sleeve valve element fitting slidably within an end ofsaid cylinder, whereby the ports in said sleeve valve element areadapted to be alternately covered and uncovered by the relativelongitudinal movement of said cylinder and said rod.

3. A paraffin scraper adapted for free longitudinal movement withinan'oil well flow pipe provided with upper and lower stops in the path ofsaid scraper, said scraper comprising a hollow cylinder having alongitudinal slot intermediate the ends thereof, a circular scraperblade attached adjacent an end of said cylinder and projecting outwardlytherefrom, a rod positioned axially within and extending longitudinallybeyond the ends of said cylinder, said rod having a lateral extensionintermediate the ends thereof fitting slidably within said slot in saidcylinder, said extension and said slot cooperating to limit the relativelongitudinal movement of said cylinderl and said rod when said rodstrikes a stop, a cup shaped sleeve valve element having ports thereinmounted on said rod adjacent an end thereof, said sleeve valve elementfitting slidably within an end of said cylinder, whereby the ports insaid sleeve valve element are adapted to be alternately covered anduncovered by the relative longitudinal movement of said cylinder andsaid rod, arcuate positioning springs carried by said rod and contactingsaid cylinder, an inwardly extending annular neck on said cylinderposition substantially mid-way between the extreme limits of movement ofsaid springs with respect to said cylinder, whereby said springsposition said rod centrally within said cylinder and cooperate with saidneck to maintain said rod in either extreme longitudinal position withrespect to said cylinder.

4. A paran scraper adapted for free longitudinal movement within an oilwell flow pipe, said scraper comprising a hollow cylinder provided withlongitudinal slots adjacent the upper end thereof, a rod axiallypositioned within and extending longitudinally beyond the ends of saidhollow cylinder and adapted for relative longitudinal movement withrespect to said hollow cylinder, a solid cylindrical member integrallyattached to the upper end of said hollow cylinder above said slots, saidsolid cylindrical :member being provided with a longitudinal channel andsaid rod extending through and slidably tting in said longitudinalchannel, an enlarged head portion at the upper end of said rod abovesaid solid cylindrical cylinder and projecting outwardly therefrom, andvalve to the lower end of said rod and fitting slidably within the lowerend of said hollow cylinder.

References Cited in the file of this patent means comprising a slottedcup-shaped member attached 10 2,655,996

UNITED STATES PATENTS Festervan et al Aug. 10, 1943 Williams Apr. 28,1953 Hodges Sept. 15, 1953 Earl et al Oct. 20, 1953

